I've been following drug policy around the world for decades. The reason it is so interesting (and so pernicious) is because it's a big jumble of counterintuitive, niggling details and unintended consequences that defies common sense.

Of course cough medicine isn't any more mind altering than caffeine - except that there at least two types of highly psychoactive cough medicine: opioid, which has narcotic effects, and dextromethorphan, which has dissociative effects.

Experts, including Dr. Toshihiko Matsumoto, claim that wrist-cutting, suicides, and other self-harm increases when it becomes more difficult for young people to purchase cough syrup, presumably because they use it self-medicate trauma.

This is a microcosm for drug policy in general. Prohibition is only successful if you ignore second-order effects.

None of this is to discourage you from learning more about drug policy. Maybe if more people learned about it we would stop repeating the same mistakes over and over again